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Merged
youknowone merged 3 commits into from
Dec 28, 2025
Merged

tp_itemsize #6544

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028c05f
itemsize
youknowone Dec 26, 2025
55f99ee
badslot
youknowone Dec 26, 2025
8a89e3c
Auto-format: cargo fmt --all
github-actions[bot] Dec 27, 2025
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Auto-format: cargo fmt --all
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@github-actions
github-actions[bot] committed Dec 27, 2025
commit 8a89e3c9a61387f47adeab444fbf590c6874e113
229 changes: 115 additions & 114 deletions crates/vm/src/builtins/type.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1352,143 +1352,144 @@ impl Constructor for PyType {
attributes.insert(identifier!(vm, __hash__), vm.ctx.none.clone().into());
}

let (heaptype_slots, add_dict): (Option<PyRef<PyTuple<PyStrRef>>>, bool) =
if let Some(x) = attributes.get(identifier!(vm, __slots__)) {
// Check if __slots__ is bytes - not allowed
if x.class().is(vm.ctx.types.bytes_type) {
return Err(vm.new_type_error(
"__slots__ items must be strings, not 'bytes'".to_owned(),
));
}

let slots = if x.class().is(vm.ctx.types.str_type) {
let x = unsafe { x.downcast_unchecked_ref::<PyStr>() };
PyTuple::new_ref_typed(vec![x.to_owned()], &vm.ctx)
} else {
let iter = x.get_iter(vm)?;
let elements = {
let mut elements = Vec::new();
while let PyIterReturn::Return(element) = iter.next(vm)? {
// Check if any slot item is bytes
if element.class().is(vm.ctx.types.bytes_type) {
return Err(vm.new_type_error(
"__slots__ items must be strings, not 'bytes'".to_owned(),
));
}
elements.push(element);
}
elements
};
let tuple = elements.into_pytuple(vm);
tuple.try_into_typed(vm)?
};

// Check if base has itemsize > 0 - can't add arbitrary slots to variable-size types
// Types like int, bytes, tuple have itemsize > 0 and don't allow custom slots
// But types like weakref.ref have itemsize = 0 and DO allow slots
let has_custom_slots = slots
.iter()
.any(|s| s.as_str() != "__dict__" && s.as_str() != "__weakref__");
if has_custom_slots && base.slots.itemsize > 0 {
return Err(vm.new_type_error(format!(
"nonempty __slots__ not supported for subtype of '{}'",
base.name()
)));
}

// Validate slot names and track duplicates
let mut seen_dict = false;
let mut seen_weakref = false;
for slot in slots.iter() {
// Use isidentifier for validation (handles Unicode properly)
if !slot.isidentifier() {
return Err(vm.new_type_error("__slots__ must be identifiers".to_owned()));
}

let slot_name = slot.as_str();
let (heaptype_slots, add_dict): (Option<PyRef<PyTuple<PyStrRef>>>, bool) = if let Some(x) =
attributes.get(identifier!(vm, __slots__))
{
// Check if __slots__ is bytes - not allowed
if x.class().is(vm.ctx.types.bytes_type) {
return Err(
vm.new_type_error("__slots__ items must be strings, not 'bytes'".to_owned())
);
}

// Check for duplicate __dict__
if slot_name == "__dict__" {
if seen_dict {
let slots = if x.class().is(vm.ctx.types.str_type) {
let x = unsafe { x.downcast_unchecked_ref::<PyStr>() };
PyTuple::new_ref_typed(vec![x.to_owned()], &vm.ctx)
} else {
let iter = x.get_iter(vm)?;
let elements = {
let mut elements = Vec::new();
while let PyIterReturn::Return(element) = iter.next(vm)? {
// Check if any slot item is bytes
if element.class().is(vm.ctx.types.bytes_type) {
return Err(vm.new_type_error(
"__dict__ slot disallowed: we already got one".to_owned(),
"__slots__ items must be strings, not 'bytes'".to_owned(),
));
}
seen_dict = true;
elements.push(element);
}
elements
};
let tuple = elements.into_pytuple(vm);
tuple.try_into_typed(vm)?
};

// Check for duplicate __weakref__
if slot_name == "__weakref__" {
if seen_weakref {
return Err(vm.new_type_error(
"__weakref__ slot disallowed: we already got one".to_owned(),
));
}
seen_weakref = true;
}
// Check if base has itemsize > 0 - can't add arbitrary slots to variable-size types
// Types like int, bytes, tuple have itemsize > 0 and don't allow custom slots
// But types like weakref.ref have itemsize = 0 and DO allow slots
let has_custom_slots = slots
.iter()
.any(|s| s.as_str() != "__dict__" && s.as_str() != "__weakref__");
if has_custom_slots && base.slots.itemsize > 0 {
return Err(vm.new_type_error(format!(
"nonempty __slots__ not supported for subtype of '{}'",
base.name()
)));
}

// Check if slot name conflicts with class attributes
if attributes.contains_key(vm.ctx.intern_str(slot_name)) {
return Err(vm.new_value_error(format!(
"'{}' in __slots__ conflicts with a class variable",
slot_name
)));
}
// Validate slot names and track duplicates
let mut seen_dict = false;
let mut seen_weakref = false;
for slot in slots.iter() {
// Use isidentifier for validation (handles Unicode properly)
if !slot.isidentifier() {
return Err(vm.new_type_error("__slots__ must be identifiers".to_owned()));
}

// Check if base class already has __dict__ - can't redefine it
if seen_dict && base.slots.flags.has_feature(PyTypeFlags::HAS_DICT) {
return Err(
vm.new_type_error("__dict__ slot disallowed: we already got one".to_owned())
);
}
let slot_name = slot.as_str();

// Check if base class already has __weakref__ - can't redefine it
// A base has weakref support if:
// 1. It's a heap type without explicit __slots__ (automatic weakref), OR
// 2. It's a heap type with __weakref__ in its __slots__
if seen_weakref {
let base_has_weakref = if let Some(ref ext) = base.heaptype_ext {
match &ext.slots {
// Heap type without __slots__ - has automatic weakref
None => true,
// Heap type with __slots__ - check if __weakref__ is in slots
Some(base_slots) => base_slots.iter().any(|s| s.as_str() == "__weakref__"),
}
} else {
// Builtin type - check if it has __weakref__ descriptor
let weakref_name = vm.ctx.intern_str("__weakref__");
base.attributes.read().contains_key(weakref_name)
};
// Check for duplicate __dict__
if slot_name == "__dict__" {
if seen_dict {
return Err(vm.new_type_error(
"__dict__ slot disallowed: we already got one".to_owned(),
));
}
seen_dict = true;
}

if base_has_weakref {
// Check for duplicate __weakref__
if slot_name == "__weakref__" {
if seen_weakref {
return Err(vm.new_type_error(
"__weakref__ slot disallowed: we already got one".to_owned(),
));
}
seen_weakref = true;
}

// Check if __dict__ is in slots
let dict_name = "__dict__";
let has_dict = slots.iter().any(|s| s.as_str() == dict_name);

// Filter out __dict__ from slots
let filtered_slots = if has_dict {
let filtered: Vec<PyStrRef> = slots
.iter()
.filter(|s| s.as_str() != dict_name)
.cloned()
.collect();
PyTuple::new_ref_typed(filtered, &vm.ctx)
// Check if slot name conflicts with class attributes
if attributes.contains_key(vm.ctx.intern_str(slot_name)) {
return Err(vm.new_value_error(format!(
"'{}' in __slots__ conflicts with a class variable",
slot_name
)));
}
}

// Check if base class already has __dict__ - can't redefine it
if seen_dict && base.slots.flags.has_feature(PyTypeFlags::HAS_DICT) {
return Err(
vm.new_type_error("__dict__ slot disallowed: we already got one".to_owned())
);
}

// Check if base class already has __weakref__ - can't redefine it
// A base has weakref support if:
// 1. It's a heap type without explicit __slots__ (automatic weakref), OR
// 2. It's a heap type with __weakref__ in its __slots__
if seen_weakref {
let base_has_weakref = if let Some(ref ext) = base.heaptype_ext {
match &ext.slots {
// Heap type without __slots__ - has automatic weakref
None => true,
// Heap type with __slots__ - check if __weakref__ is in slots
Some(base_slots) => base_slots.iter().any(|s| s.as_str() == "__weakref__"),
}
} else {
slots
// Builtin type - check if it has __weakref__ descriptor
let weakref_name = vm.ctx.intern_str("__weakref__");
base.attributes.read().contains_key(weakref_name)
};

(Some(filtered_slots), has_dict)
if base_has_weakref {
return Err(vm.new_type_error(
"__weakref__ slot disallowed: we already got one".to_owned(),
));
}
}

// Check if __dict__ is in slots
let dict_name = "__dict__";
let has_dict = slots.iter().any(|s| s.as_str() == dict_name);

// Filter out __dict__ from slots
let filtered_slots = if has_dict {
let filtered: Vec<PyStrRef> = slots
.iter()
.filter(|s| s.as_str() != dict_name)
.cloned()
.collect();
PyTuple::new_ref_typed(filtered, &vm.ctx)
} else {
(None, false)
slots
};

(Some(filtered_slots), has_dict)
} else {
(None, false)
};

// FIXME: this is a temporary fix. multi bases with multiple slots will break object
let base_member_count = bases
.iter()
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